Alexa app sees Hue bulbs, but won't respond to voice command

Just upgraded our G1 Echo to a new Echo Plus. Thought I'd celebrate by adding 2 new Hue bulbs -- 1 for each lamp in the master bedroom. (We already have a Hue bridge that my son uses to control the lights in his bedroom.)

The Hue app immediately recognized the new bulbs and I set them up as His Lamp and Her Lamp, and put them in a Room called Master Bedroom.

Hopped over to the Alexa app and Discovery found His Lamp, Her Lamp, and Master Bedroom, and added all 3.

If I ask Alexa to turn on "Master Bedroom lights", she turns both lamps on and off, no problem.

But if I ask Alexa to turn on "His Lamp" or "Her Lamp", she responds and tells me she cannot find a device with either name, even though I can clearly see them on the Alexa app device list, and I can even control them manually in both the Alexa app and the Hue app. It's just voice commands with Alexa that doesn't work.

My son suggested removing them from the "Master Bedroom" room in the Hue app, and assigning each lamp to its own "room" in the Hue app, just so see if we can get them working individually. I did, and ran discovery again. Same problem -- I can see and control them manually in the app, but voice commands don't work.

Ideally, I'd like to be able to set up Alexa to turn on each lamp individually via voice, or both at once with the Master Bedroom command. What am I missing here?

Update: I was able to get the 2 Hue bulbs to work with Alexa by changing the names to Mom's Lamp and Dad's Lamp. Not sure why it wouldn't work with the original chosen names, but whatever. Also, not 100% pleased with the name choice so I might end up re-naming them and see what happens.

If anyone has any idea as to why the original names couldn't work with Alexa, I'm all ears.